Reducing viscosity of cellulose nitrate with morpholine



Patented Apr. 12, 1949 REDUCKNG VISCOSITY OF CELLULOSE NITRATE WITHMORPHOLINE Stewart B. Luce, Springfield, Mass., assignor to MonsantoChemical Company, St. Louis, Mo., a corporation of Delaware No Drawing.Application November 20, 1943, Serial No. 511,185

8 Claims. (Cl. 260-223) This invention relates to the reduction inviscosity of cellulose nitrate.

It is known that the viscosity of cellulose nitrate may be reduced, forexample, by steam digestion under high pressure. However, such methodsrequire complicated and expensive apparatus to insure safe operatingconditions. Other prior processes lead to products possessing poor colorand/or requiring expensive purifrcation.

An object of this invention is to provide an improved method forreducing the viscosity of cellulose nitrate. A further object of thisinvention is to provide a process for reducing the viscosity ofcellulose nitrate with substantially no discoloration or decompositionthereof. Still another object is to provide a method for reducing theviscosity of cellulose nitrate at moderate temperatures and pressuresthereby eliminating explosive hazards of high temperature and pressuremethods.

According to the present invention, the viscosity of cellulose nitrateis reduced by treatment with a 'morpholine compound. By operatingaccording to this invention the viscosity of cellulose nitrate may bereduced under far less hazardous conditions than have characterizedcertain prior methods and/or other advantageous results may be obtained.

By a morpholine compound is meant a compound possessing the structuralformula or derivative thereof wherein one or more of the hydrogens maybe substituted by monovalent organic radicals, for example, arylradicals such as phenyl, naphthyl, halogeno-phenyl (chlorophenyl),hydroxy phenyl, alkoxy phen'yl; al-

kylated aryl radicals such as toluyl; alkyl radia desirable. Theduration of the treatment depends on the degree of viscosity reductiondesired in the cellulose nitrate and the temperatures and otherconditions employed. In general, from 0.1% to 10% by weight of amorpholine compound is employed, based on the amount of cellulosenitrate. According to a preferred embodiment from 0.5% to 3% of amorpholine compound is employed.

The cellulose nitrate employed may be prepared from wood pulp, cottonlinters or other suitable source of cellulose. According to my inventionthe cellulose nitrate may be treated in solution or in the solid statewhen in the form of fibres or other finely divided form. The viscosityof the cellulose nitrate employed may be widely varied. In fact aparticularly advantageous feature of this invention resides in the factthat cellulose nitrate of high viscosity, for example, 1000 secondsviscosity or more may be readily made available for use in lacquers,plastics, etc., wherein low viscosities are necessary, for example 0.25-seconds, while maintaining substantially the nitrogen content, color,etc., of the original material. This makes possible material savings inthe cost of the final product since, as is known, the initialpreparation of high viscosity cellulose nitrate is far more economicalthan that of low viscosity cellulose nitrate.

By proper combination of the conditions of treatment of cellulosenitrate with a morpholine compound according to this invention, productsmay be prepared having varying viscosities, for example, as low as 0.25second or even lower.

The following are specific examples illustrative of the presentinvention but not limitative thereof.

The stability and viscosity values given in the examples are determinedin accordance with the A. S. T. M. D301-33 methods entitledSpecifications and Tests for Soluble Nitrocellulose.

Example I 40 grams of cellulose nitrate having a nitrogen content of12%, a viscosity of 49.6 seconds and a stability of over 25 minutes wereslurried with 500 cc. of water and 0.4 gram of morpholine and theresulting slurry heated at atmospheric pressure for 12 hours at -95 C.The slurry was then centrifuged and the separated cellulose nitratewashed and. dried. The product had a viscosity of 15.4 seconds.

Ewample II 40 grams of cellulose nitrate like that of Example I, exceptthat the viscosity was 40 seconds, were slurried with 500 cc. of waterand 1 gram of morpholine. The resulting slurry was heated for 4 hours at90-95 C. and at atmospheric pressure and was then centrifuged, and theseparated cellulose nitrate washed and dried. The resulting cellulosenitrate had a viscosity of 0.6 second.

Example III A slurry containing 100 parts of cellulose nitrate like thatof Example Lbut having a viscosity of 8.6 seconds, 2.5 parts ofmorpholine and 1250 parts of water was heated at 90-95 C. at atmosphericpressure, then centrifuged, and the separated cellulose nitrate washedand dried. By varying the time of reaction, varying degrees of viscosityreduction were obtained as shown in the following table:

. 1 Duration I of Heating Viscosity Hours Seconds Example IV Example V Aslurry containing 100 parts of cellulose nitrate like that used inEXample I, but having a viscosity of 19.3 seconds, 2.5 parts ofmorpholine and 1250 parts of water was heated for 4 hours at 9095 C. andat atmospheric pressure. It was then centrifuged, washed and theseparated cellulose nitrate bleached as 'in Example IV to yield acellulose nitrate of pale color having a viscosity of 0.9 second and anitrogen content of 11.59%.

In contrast to the foregoing a second sample of the samecellulose'nitrate heated for 2 hours at90- 95 C. with 2% of its weightof ammonia in aqueous solution produced a dark brown cellulose nitratehaving a viscosity of 0.6 second.

Example VI 10 grams of cellulose nitrate like that of Example I, buthaving a viscosity of 40.1 seconds, were placed in a glass tube, 30 cc.of water and 0.05 gram of morpholine were then added and the tube wassealed. The sealed tube was then placed in a capped iron tube andthe-whole placed in a heated circulating oil bath and then heated at'135C. for 4 hours. After cooling, the glass tube was opened, the contentscentrifuged and the separated cellulose nitrate washed and dried. Theproduct had a viscosity of 0.18 second and a nitrogen content of 11.8%.

Example VII 10 grams of cellulose nitrate'like that of Example I, buthaving a'viscosity of-1004 seconds 4 were heated as in Example VI inadmixture with 0.15 gram of morpholine and 35 cc. of water at C. in asealed tube for 4 hours. The product was centrifuged and the separatedcellulose nitrate washed and dried. The resultant cellulose nitrate hada viscosity'0f-0.18 second and a nitrogen content of 11.5%.

It is found that products prepared as described in the above examplesrequire no stabilization treatment to prevent rapid discoloration ordecrease in viscosity on aging. This is in contrast to productsprepared, for example, by treatment with ammonia or pyridine, whichrequire extensive treatment, for example, with boiling water or chemicalreagents to provide a, stabilized product that will not rapidly discoloror decrease in viscosity on aging.

Cellulose nitrate initially having a stability of not over 25 minutescontinues to meet this stability requirement after treatment accordingto this invention, as exemplified by Examples I-VII. In fact,unstabilized cellulose nitrate may even be rendered substantially stableaccording to the A. S. T. M. 13301-33 test conditions as a result of theviscosity"reduction treatment according to this invention.

It is to be further noted from the examples that the cellulose nitratemay be bleached after the viscosity has been reduced, by the procedureswell known in the industry to obtain especially light colored products.

In place of cellulose nitrate having a nitrogen content of 12% which isnormally used for making nitrocellulose lacquers, coatings, etc.,cellulose nitrate containing other percentages of nitrogen, for example,from 10.5% to 12.5% may be used. Cellulose nitrate containing about 11%nitrogen may be reduced in viscosity'by the process of this invention toyield materials especially useful, for example, in extrusion and otherprocesses for forming cellulose nitrate plastic compositions.

Other reaction media than water may be used according to the process ofthis invention. Thus, a slurry may be made using a liquid non-solventfor the cellulose nitrate such as, for example, toluol, hexane, carbontetrachloride, etc. When desired, the reaction may be carried outinsolu- :tion by substituting for the Water shown in the above examplesan active solvent for cellulose nitrate such as, for example, aliphaticalcohols including methanol, ethanol, propanol, isopropanol, butanoi,isobutanol, etc., as Well as ketones including acetone, methyl ethylketone, diethyl ketone, etc. Varying degrees of dilution of the slurryor solution may be employed. Treatment in solution is especiallydesirable when it is desired to prepare low viscosity cellulose nitratefrom scrap cellulose nitrate plastic.

What is claimed is:

1. A process for reducingthe-viscosity of cellulose nitrate whichcomprises treating cellulose nitrate with morpholine.

2. A process for reducing the viscosity of cellulose nitrate whichcomprises treating cellulose nitrate in a slurry with morpholine.

3. A process for reducing the viscosity of cellulose nitrate whichcomprises treating cellulose nitrate in solution with morpholine.

4. A process for reducing the-viscosity of cellulose nitrate whichcomprises treating cellulose nitrate in an aqueous slurry withmorpholine.

5. A process for reducing the viscosity of cellulose nitrate whichcomprises "treating 'anaqueous slurry containing cellulose nitrate withmorphollne at 20-150 C.

6. A process for reducing the viscosity of cellulose nitrate whichcomprises heating an aqueous slurry containing cellulose nitrate andmorpholine at a pressure between 1 and 6 atmospheres.

7. A process for reducing the viscosity of cellulose nitrate whichcomprises treating an aqueous slurry containing cellulose nitrate and0.1% to 10.0% by weight of morpholine based on the cellulose nitrate, at20150 C. and at 1 to 6 atmospheres pressure.

8. In the process of reducing the viscositysof cellulose nitrate, thesteps comprising heating an aqueous slurry of cellulose nitrate infinely divided 15 6 form and 0.1 to about 10% by weight of morpholinebased on the cellulose nitrate and then separating the finely dividedcellulose nitrate from said slurry.

STEWART B. LUCE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,648,509 Seel Nov. 8, 19271,9461967 Eskew Feb. 6, 1934 2,292,332 D'Alelio Aug. 4, 1942

